Electronic computing devices have become increasingly important to data computation, analysis and storage in our modern society. Modern direct access storage devices (DASDs), such as hard disk drives (HDDs), are heavily relied on to store mass quantities of data for purposes of future retrieval. As such long term data storage has become increasingly popular, and as the speed of microprocessors has steadily increased over time, the need for HDDs with greater storage capacity to store the increased amount of data has also steadily increased.
Consequently, there are seemingly constant development efforts to improve the areal density of the media implemented in hard disk drives, where the areal density is typically measured as the product of bits per inch (“BPI”) and tracks per inch (“TPI”). BPI refers to the number of bits that can be written and later reread per linear inch along a track, whereas TPI refers to the number of individual tracks per radial inch. Furthermore, additional and significant improvements are taking place which fundamentally change how HDDs record data onto the media, such as with patterned media, perpendicular magnetic recording (PMR), thermally assisted recording (TAR), and combinations of the same.
Advancements in areal density result in very narrow data tracks and, therefore, during writing and reading operations it becomes more and more difficult to align the read/write head precisely and accurately at an optimal “on track” location over the recording track. Consequently, data recovery procedures (DRP), which are internal procedures that an HDD performs to locate data in response to a read miss, are playing an increasingly significant role in system performance. This is especially true with HDDs designed for server applications, which typically need to comply with more stringent response time requirements.